The present invention relates generally to ceramic valves, and is directed in particular to an improved ceramic gate valve being formed from ceramic functional components for use in controlling the flow of high temperature and/or corrosive fluids.
In the prior art, a popular and useful form of valve structure is the gate valve, which has been widely used due to its favorable characteristics of ease and responsiveness of operability, control of flow, and efficient sealing qualities for closing off the flow in the conduit pipe. Typically, in the prior art such gate valves have been formed of metallic materials which have had a limited use for certain applications where high temperature and/or corrosive fluids were to be conducted through the conduit pipe. Continued use of the metallic gate valves in such environments has resulted in degradation of the metallic components, such as the valve gate and valve seat, due to chemical action. Yet additionally, the metallic springs that have been used to urge the valve seat into sealing engagement with the valve gate have become rapidly annealed, and thus rapidly lose usefulness as springs in high temperature environments. These and other difficulties render such prior art metallic gate valve structures to be of limited usefulness and/or useful life in these environments.
One attempt to solve these problems has been the use of ceramic components for the functional parts of the gate valve which come in contact with the corrosive and/or high temperature environment. One such attempt is proposed in U.S. Pat. No. 3,614,061. However, under this approach to a valve structure it has been necessary to eliminate entirely the spring means for urging the valve seat into operable and sealing engagement with the valve gate. Perhaps while ameliorating somewhat the problems associated with the prior art metallic valve gate structures, this proposed structure has introduced a new and even more fundamental debilitating characteristic rendering the apparatus to be of limited usefulness. This is the characteristic of incorrect pressure exerted by the valve seat on the valve gate. If the valve seat is made too small in thickness, there is insufficient pressure on the valve gate in the closed position and leaking of the valve results. If the valve seat is made too thick, the valve gate experiences difficulty in being retracted and/or results in wearing owing to excessive friction during operation of the valve. Accordingly, the dimensions of the various components in order to be functional must be set forth with great precision, which leads directly to a less than optimal production cost of the apparatus, and reduces effective life when frictional wear inevitably occurs. At that point, the only solution to the newly created problem is to replace the worn components, which increases maintenance costs.
Accordingly, in view of the shortcomings and disadvantages of the prior art, it is an object of the present invention to provide an improved ceramic gate valve apparatus having a ceramic spring disposed exterior of the valve seat for urging the same into operable engagement with the valve seat at a sufficient pressure to effect proper sealing therebetween.
It is an additional object of the improved ceramic gate valve apparatus of the present invention to provide a structure which will accomplish optimal sealing characteristics, and will do so over an extended period of time.
It is also an object of the improved ceramic gate valve structure of the present invention to provide a ceramic spring urged valve which will maintain proper inward pressure and sealing engagement between the valve and the valve seat even at high and otherwise annealing temperatures.
These and other objects and advantages of the improved ceramic valve gate structure of the present invention will become more apparent upon a review of the description of the invention and preferred embodiments, the drawing, and the claims, as set forth hereinbelow.